1. Field of the Invention
The present invention relates to an optical communication system that comprises, as part of an optical fiber network, a multi-core fiber having a cross-section in which a plurality of cores are two-dimensionally arrayed, and to an arrangement converter which serves as a connector that can be adopted by the optical communication system and which enables a favorable optical link between various network resources.
2. Related Background of the Invention
A so-called Passive Optical Network (PON) system, in which a single optical fiber is shared by customers by including a multistage optical splitter, as shown in FIG. 17, for example, has conventionally been implemented to provide FTTH (Fiber To The Home) services, which enables optical communications between a single transmitter station and a plurality of customers.
Namely, the PON system shown in FIG. 17 comprises a terminal station 1 (transmitter station), which is the final relay station of an existing communication system such as the Internet, and an optical fiber network that is laid between the terminal station 1 and a customer premises 2 (customer). The optical fiber network is configured by a closure (including an optical splitter 30) that is provided as a branching point, an optical communication line 12 from the terminal station 1 to the closure, and an optical communication line 31 from the closure to each customer premises 2.
The terminal station 1 comprises an Optical Line Terminal (OLT) 10 and an optical splitter 11 that splits a multiplexed signal from the OLT 10. Meanwhile, an Optical Network Unit (ONU) 20 is provided in the customer premises 2. At least the optical splitter 30 for further splitting an incoming multiplexed signal and a wavelength-selective filter for restricting the service content or the like are installed in the closure, which serves as a branching point, of the optical fiber network that is laid between the terminal station 1 and the customer premises 2.
As described above, in the PON system shown in FIG. 17, an optical splitter 11 is provided in the terminal station 1, and an optical splitter 30 is provided in the closure installed in the optical fiber network, and hence FTTH services can be provided for a plurality of customers by a single optical line terminal 10.
However, a PON system, in which a plurality of customers share a single optical fiber due to the inclusion of a multistage optical splitter as described above, is actually confronted by technical problems with regard to ensuring congestion control and securing a reception timing range, and the future addition of transmission capacity. A transition to an SS (Single Star) system is considered one means of solving such technical problems (ensuring congestion control and securing a timing range and so forth). Since transitioning to an SS system involves a greater number of fibers on the station side than in a PON system, ultra-small diameter and ultra-high density cables are required for the optical cables installed on the station side. Multicore fibers are suitable as the optical fibers for achieving a smaller diameter and an ultra-high density.
For example, as a multicore fiber, the optical fiber disclosed by Japanese Patent Application Laid-Open No. 05-341147 (Document 1) includes, in a cross-section thereof, at least seven two-dimensionally arrayed cores. Furthermore, Japanese Patent Application Laid-Open No. 10-104443 (Document 2) discloses an optical fiber which has a plurality of cores arranged in a straight line, and describes the fact that the connection between the optical waveguide and semiconductor optical integrated device is straightforward.